^6 LABORATORY BACTERIOLOGY 



EXERCISE XXVII 



BACILLUS COLT COMMUNIS 



113. Of the bacteria normally present on the mucous mem- 

 branes of the animal body the colon group is, on account of 

 its close morphological relationship to the bacilh of typhoid 

 fever and hog cholera, of more than ordinary interest. There 

 are varieties of this organism which approximate very closely 

 in their biochemic properties as well as in their morphology to 

 the typhoid and also to the hog-cholera bacilli. It is impor- 

 tant that this existing variation be recognized and that the 

 list of properties which characterize B. coli communis should 

 be clearly determined. The differentiation of the colon and 

 typhoid bacilli as they exist in nature is one of the diffi- 

 cult problems in practical bacteriological work. The culture 

 assigned approaches very closely to the typical species. 



References. Chapters on this organism in the text-books. 

 T. Smith, The Am. Jour, of Med. Sci., September, 1896. Adelaide 

 W. Peckham, Jour, of Exp. Med., Vol. II (1897), p. 549. Adami, 

 Ibid., Vol. IV (1S99), p. 349. Gage and Phelps, Report Am. 

 Pub. Health Asso., 1902, p. 402. Moore and Wright, Am. Med., 

 Vol. Ill (1902), p. 504. 



114. Work for this exercise. Describe the appearance of 

 each of the cultures of B. coli communis made in Exercise 

 XXVI. 



Examine the bacteria in a hanging-drop preparation from 

 the bouillon and glucose bouillon cultures. 



Make and stain with carbol fuchsin a cover-glass preparation 

 from the agar culture. Measure a few of the bacilli and 

 record their size in the notes. 



Note especially the quantity of gas formed in each of the 

 fermentation tubes. These cultures should be kept until the 



